Democratic presidential candidates Hillary Clinton and Sen. Bernie Sanders, Vermont independent, stand together before the start of the Univision/Washington Post Democratic presidential debate at Miami-Dade College in Miami on March 9, 2016. (Associated Press) **FILE** more >

Sen. Bernard Sanders of Vermont has a narrow edge in Missouri and is close to former Secretary of State Hillary Rodham Clinton in Ohio and Illinois ahead of big contests on Tuesday in the Democratic presidential primary race.

Mr. Sanders had a 1-point, 47 percent to 46 percent, lead over Mrs. Clinton in Missouri, according to polling released Monday by the Democratic-leaning firm Public Policy Polling.

Mrs. Clinton, meanwhile, had a 5-point lead in Ohio, 46 percent to 41 percent, and a 3-point lead in Illinois, 48 percent to 45 percent.

Mr. Sanders is looking for a repeat performance in the Midwest; he scored a major upset over Mrs. Clinton last week in Michigan after trailing by some 20 points in polling leading up to the March 8 contest.

The PPP polling showed that Mr. Sanders could stand to benefit from independent and Republican voters planning to vote in the Democratic contests. Mrs. Clinton led by between 17 and 22 points among Democrats in each state, but Mr. Sanders led by between 33 and 51 points among independents and between 35 and 43 points among Republicans in each state.

In North Carolina and Florida, two other states voting Tuesday, Mrs. Clinton had a more sizable advantage. She led by 25 points in Florida — a closed primary state — 57 percent to 32 percent. And she had a 19-point, 56 percent to 37 percent, lead in North Carolina.